1. Field of the Invention
The invention relates to a data recording medium, data recording apparatus and method, and data reproducing apparatus and method which can be applied to a plurality of kinds of optical discs having, for example, different recording densities.
2. Description of the Related Art
In recent years, an optical disc as a recording medium of a large capacity has been being developed. For example, there are read only discs such as CD (Compact Disc) on which music information has been recorded, CD-ROM in which data for a computer has been recorded, and the like. In those optical discs, a sub-code having eight channels (P, Q, R, S, T, U, V, W) is prepared together with audio data or the like, and time information of the audio data or digital data has been recorded in data of 72 bits in the Q channel.
The time information includes: an absolute time as a reproduction elapsed time from the head of a recording area on a CD or the like; and a relative time (elapsed time in a movement) as a reproduction elapsed time from the head of each music piece or each index. Those time information is BCD (Binary Coded Decimal) coded by two digits in a format (referred to as an MSF format) in which a minute (MIN), a second (SEC), and a frame number (FRAME) are used as units. In the ordinary CD, one second corresponds to 75 frames and the absolute time within a range from a 00min00sec00frame to a 99min59sec74frame can be expressed (however, according to the standard of the CD, the absolute time is set to be shorter than 80 minutes). In case of the CD-ROM, those time information shows address information of the digital data.
In recent years, optical discs in which data can be written once, data is rewritable, and the like such as WORM-type (Write Once Read Mostly) CD-R (CD-Recordable), rewritable-type CD-RW (CD-Rewritable), and the like have been being put into practical use. In those discs, recording address information called ATIP (Absolute Time In Pre-groove) is frequency modulated and expressed by a BCD expression by the MSF format into a guide groove (pre-groove) wobbled by a sinewaveform of 22.05 kHz.
A high density optical disc in which a capacity and a density of the optical disc as mentioned above are increased is strongly demanded in the market. In the high density optical disc, inconvenience occurs in the case where the conventional absolute time expression is used as it is. That is, under the absolute time expression of up to 99min59sec74frame, it is impossible to cope with a high density disc having a large capacity.
To solve the above problem, in case of the high density disc, the use of time information which can express addresses of a large capacity is considered. The time information differs from the time information recorded on the existing disc. It is necessary that processes at the time when the time information of different formats exist mixedly as mentioned above are properly executed. For example, although the time information is usually displayed, it is desirable that the time information of the high density disc can be displayed by a method whereby a feeling of difference from that of the display of the time information of the existing disc is small.
To promptly execute processes, it is important to rapidly make a discrimination of the type of disc about whether the disc loaded in a reproducing apparatus is an ordinary disc or a high density optical disc or the like, or the like. That is, unless the type of disc can be discriminated prior to a demodulating process of data recorded on the optical disc, it is unknown how to set internal processes or dedicated hardware of the apparatus which depend on the type of disc. Therefore, the number of trials increases and a necessity of performing a troublesome disc discriminating process occurs. To avoid such a situation, a method of discriminating whether the optical disc is the conventional disc or the high density optical disc or the like without increasing a burden on the reproducing apparatus is strongly demanded.
It is, therefore, an object of the invention to provide a data recording medium, data recording apparatus and method, and data reproducing apparatus and method which are effective when they are applied to a case where different kinds of time information or addresses exist mixedly.
According to the invention of claim 1, there is provided a disc-shaped recording medium in which information is recorded by a recording format based on a CD format,
wherein the medium has a sub-code area in which a sub-code as additional information is recorded,
the sub-code area has a Q channel for recording address information which shows a recording position of the information which is recorded on the disc-shaped recording medium and includes absolute time information shown by each unit of xe2x80x9chourxe2x80x9d, xe2x80x9cminutexe2x80x9d, xe2x80x9csecondxe2x80x9d, and xe2x80x9cframexe2x80x9d, and
the Q channel is defined on the basis of the CD format and a zero-data area in the Q channel has an AHOUR area in which time information shown by the xe2x80x9chourxe2x80x9d unit in the absolute time information is recorded.
According to the invention of claim 14, there is provided a data recording apparatus for recording main data and time information accompanied for the main data into a recording medium, comprising:
identifying means for identifying a type of the recording medium;
data converting means for outputting the time information and switching a format of the time information which is outputted in accordance with the type of the recording medium; and
recording means for recording the time information outputted from the data converting means together with the main data into the recording medium.
According to the invention of claim 24, there is provided a data recording method of recording main data and time information accompanied for the main data into a recording medium, comprising the steps of:
identifying a type of the recording medium;
converting time information in a first format in the time information which is expressed by a plurality of different formats into time information in a second format different from the first format in accordance with the type of the recording medium; and
recording the converted time information together with the main data into the recording medium.
According to the invention of claim 30, there is provided a data recording method of recording main data and time information accompanied for the main data into a recording medium, comprising the steps of:
identifying a type of the recording medium;
forming selected time information in the time information which is expressed by a plurality of different formats in accordance with the type of the recording medium; and
recording the formed time information together with the main data into the recording medium.
According to the invention of claim 36, there is provided a data reproducing apparatus for reproducing a recording medium in which main data and time information accompanied for the main data have been recorded, comprising:
identifying means for identifying a type of the recording medium;
pickup means for reading the time information recorded in the recording medium;
demodulating means for switching a format of the time information outputted from the pickup means in accordance with the type of the recording medium; and
reproducing means for reproducing or displaying the time information outputted from the demodulating means.
According to the invention, an expansion of an expression of the time information, a recording of discrimination information regarding the disc type or the like, or the like can be performed by using an area of a relatively low significance among areas in which the additional information has been recorded. In the case where a plurality of kinds of data recording media can be reproduced, the problem such that the displays of the time information exist mixedly can be avoided.
The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings.